int exp_fdf (const gsl_vector * x, void *params, gsl_vector * f, gsl_matrix * J) { exp_f (x, params, f); exp_df (x, params, J); return GSL_SUCCESS; }
inline static int exp_fdf (const gsl_vector * x, void *data, gsl_vector * f, gsl_matrix * J) { exp_f (x, data, f); exp_df (x, data, J); return GSL_SUCCESS; }